No progress bar on migration assistant?

I just took delivery of a new MacBook Air with the M1 chip and I'm using Migration Assistant to transfer everything from my old MacBook Air. I'm using the latest Time Machine backup on an portable hard drive. All was going well with the onscreen prompts and I allowed all the boxes to remain checked as for what users and files to transfer (all of them) and pressed "continue". I was presented with the opportunity to create secure passwords for all users, which I did and was shown tiny green checkmarks next to each. Then... nothing. No progress bars, not time remaining, no spinning ball, nothing.

How am I to know if anything is happening? The two options at the bottom of the screen are "back" or "continue" but the "continue" box is greyed out. The light on the portable hard drive is but a slow pulsing light but with no sound of activity. Is this normal and I should just wait? For how long? Should there be a progress bar.. something? BTW there's only about 200GB of data to transfer onto the 512GB new drive.

Thanks;